Performance Limits of Direct Wideband Coherent 3D Localization in Distributed Massive MIMO Systems.

Nenad Vukmirović,Miljko Erić,Petar M Djurić

doi:10.3390/s21103401

Nenad Vukmirović, Miljko Erić + Show 1 more

Open Access

https://doi.org/10.3390/s21103401

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Abstract

We address the accuracy of wideband direct position estimation of a radio transmitter via a distributed antenna array in 5G cellular systems. Our derivations are based only on the presence of spatially coherent line-of-sight (LoS) signal components, which is a realistic assumption in small cells, especially in the mmWave range. The system model considers collocated time and phase synchronized receiving front-ends with antennas distributed in 3D space at known locations and connected to the front-ends via calibrated coaxial cables or analog radio-frequency-over-fiber links. Furthermore, the signal model assumes spherical wavefronts. We derive the Cramér-Rao bounds (CRBs) for two implementations of the system: with (a) known signals and (b) random Gaussian signals. The results show how the bounds depend on the carrier frequency, number of samples used for estimation, and signal-to-noise ratios. They also show that increasing the number of antennas (such as in massive MIMO systems) considerably improves the accuracy and lowers the signal-to-noise threshold for localization even for non-cooperative transmitters. Finally, our derivations show that the square roots of the bounds are two to three orders of magnitude below the carrier wavelength for realistic system parameters.

Highlights

There has been a growing interest in massive multiple-input multiple-output (MIMO) systems [1] and millimeter-wave communication technology [2,3,4,5,6,7]
The results show the advantage of using millimeter-wave communication (mmWave) massive MIMO systems because the localization can successfully be performed in low signal-to-noise ratio (SNR) conditions, even for unknown sequences
We have addressed the performance limits of direct wideband coherent 3D localization in distributed mmWave massive MIMO for 5th generation (5G) cellular systems

Summary

Introduction

There has been a growing interest in massive multiple-input multiple-output (MIMO) systems [1] and millimeter-wave communication (mmWave) technology [2,3,4,5,6,7]. These systems are already finding their place in future 5th generation (5G) cellular systems. A very important application of 5G systems is indoor localization and tracking [8] Their key objective is to achieve a localization accuracy of about 1 cm [9], which is satisfactory for location-based services in cellular systems. We addressed two implementations of the system: (a) with deterministic sequences known to the receiver system and (b) with random Gaussian sequences

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